Letting your child enter an area with uncontrolled guns, is child endangerment. Small children cannot be trusted to make correct choices, we do that for them. If there is an adult in your child's life that is not making correct choices for your child, and you allow your child time with that adult, you are likewise responsible for anything that happens to that child.
The first thing that goes into a house with a child, is a lockable safe. Second comes a gun.
Do not allow your child into any area with guns laying around, in the open. No safe, guns not in the safe, do not allow your child to enter that house. Plain and simple. This rule applies to 6 month olds, 2 year olds, 6 year olds, 14 year olds, or anyone not able to understand the correct use of firearms.